Point defects in semiconductors play an important role in governing the
material's electronic properties. Intrinsic point defects consist of the
displaced atoms of the lattice itself and in general form deep levels that act
as trapping centers for conduction electrons or holes. Non-paramagnetic
intrinsic centers in low concentrations are best accessible to investigation
by radioactive probe atoms placed in the atomic neighbourhood of the defect.
The decay of a radioactive atom, substitutionally incorporated into the
lattice of the semiconductor, can produce a single isolated Frenkel-pair, if
the recoil energy induced by the neutrino-emission accompanying the decay
exceeds a certain threshold energy.

The neutrino-recoil-method is used to investigate the formation of intrinsic
point defects in the two compound semiconductors InSb (n-type) and CdTe
(p-type). Radioactive Te is implanted into InSb via a proton-induced reaction,
into CdTe via a heavy-ion reaction. The subsequent decay of Te to Sb transfers
a recoil energy of 12eV to the atom, an amount that lies just above the
threshold energies in both semiconductors as they have been obtained through
electron-irradiation experiments. The following decay leads to 119Sn that is
used as a probe atom for Mößbauer-spectroscopy.

The analysis and interpretation of the experimental results require the
consideration of all available measurement parameters, namely the hyperfine
parameters isomer shift and quadrupole splitting as well as the line intensity
as a time-dependent parameter.

The results obtained in the two materials differ from each other
fundamentally. InSb displays three different types of intrinsic point defects
created by the neutrino recoil process, i.e. an interstitial site and a site
on each of its sublattices with an adjacent vacancy, whereas CdTe shows only
one, which is accompanied by an unexpectedly large field gradient. In
addition, the substitutional site in CdTe induces a significant distortion of
its local surrounding, that can be interpreted to be due to a Jahn-Teller-
effect.

Furthermore, within CdTe Sb attracts intrinsic oxygen when being anneald at
temperatures well above 600°C, a process that exhibits itself in the formation
of SnO2-complexes.